The present invention relates to the imaging of anatomic regions of a patient. More specifically, it relates to a medical system and method using ultrasound in combination with another imaging technology in order to perform a medical procedure upon a patient. The medical procedure can be a diagnostic procedure, a remedial procedure, or a combination of the two.
Among others, Frank J. Bova and William A. Friedman of the present inventors have pioneered the art of high precision planning and treatment of intracranial targets using radiation originating from medical linear accelerators. All of these previously developed planning and treatment systems have been based upon a rigid model consisting of the patient""s skull, upper dentisia and intracranial anatomy. Exemplary of these systems and methods are those described in the following U.S. Patent Nos., issued to the Bova and Friedman on the indicated dates, assigned to the assignee of the present application, the entire contents and disclosures of all of which are incorporated herein by reference:
U.S. Pat. No. 5,954,647 Marker system and related stereotactic procedure Sept. 21, 1999
U.S. Pat. No. 5,588,430 Repeat fixation for frameless stereotactic procedure Dec. 31, 1996
U.S. Pat. No. 5,189,687 Apparatus for stereotactic radiosurgery Feb. 23, 1993
U.S. Pat. No. 5,027,818 Dosimetric technique for stereotactic radiosurgery Jul. 02, 1991
Although this rigid model is valid for cranial targets, it is not practical for all anatomic regions. An example of a target that cannot be modeled with a rigid body modality is metastatic disease within the liver. In order to effect the application of high precision radiation treatments or other medical procedures to such deformable anatomic regions, real time imaging of the target region must be incorporated into the treatment procedure.
Among imaging techniques that can be considered for such real time imaging multiplanar x-rays and ultrasound are the best suited.
Multiplanar x-ray imaging, primarily orthogonal imaging, has been used to localize radiation targets for several decades. While this mode of target localization has several advantages, its primary disadvantages are the space and time it requires. The space required by the imaging chain, including x-ray source(s) and imaging electronics, is simply not available near or around a patient who is in position for real time treatment, especially if the treatment uses a medical linear accelerator. Depending on how fast an image of a given portion of the anatomy changes with time and the time required to complete a multiplanar x-ray process, the x-ray imaging may not be sufficiently fast to track changes and provide accurate real time data.
Ultrasonic imaging has the advantage of only requiring a small ultrasonic probe to be utilized near the treatment region. Therefore, it avoids the space problem common to multiplanar x-ray real time imaging during a medical procedure. However, traditional ultrasonic techniques have not generally provided for three-dimensional (3D) anatomical data without requiring movement of the ultrasound probe. Instead, and in the absence of relative movement between the probe and the patient, they have been limited to two-dimensional (2D) imaging.
It has been suggested in the past to use ultrasound for assistance in target localization in several therapeutic settings. Real time imaging of the prostate, for assistance of radioactive seed placement, has been in use for several years. Recently, a 3D real time ultrasound system has been introduced for assistance in such seed placement. This system allows the user to view the prostate in multiple planes while simultaneously introducing catheters for seed placement. Target shifts during surgery have been investigated using a single plane ultrasound probe attached to an image guidance system. The use of a single plane ultrasonic robe attached to an infrared imaging guidance system, in order to obtain surface contours for rigid model registration, has been suggested. The incorporation of a planar ultrasonic probe for anatomic localization of bony anatomy for image guided procedures involving the spine has also been attempted. Real time imaging of the prostate with a planar ultrasound probe attached to an articulating arm to aid in positioning patients for external beam linear accelerator treatments has also been commercially introduced.
The systems that have attempted 3D target localization for external beam targeting have, to date, used single plane ultrasound probes. While this technique allows the user to scan in multiple planes and ultimately reconstruct a 3D image of the target region, the necessary movement of the physical ultrasound probe has presented several significant disadvantages, including (1) the time required to obtain the initial image, (2) the movement of the anatomy as the imaging probe traverses the region, and (3) the inability to view the target region in true three dimensions during treatment when probe movement is impractical. A new ultrasound probe has been introduced which, when linked to a guidance system, can overcome these previous technical limitations.
The new ultrasound or ultrasonic probe was recently introduced by Medison Company. This probe provides a 3D image of an anatomic region without external probe movement. U.S. Pat. No. 5,893,832, issued to Song on Jun. 24, 1997, and assigned on its face to Medison, describes an ultrasound probe, which is able to overcome some of the above-described disadvantages. The probe effectively provides a 3D image of a selected anatomic region without the necessity for external probe movement.
Ultrasound probes like those of the Song patent can provide real time imaging of a portion of the patient""s anatomy. However, the image data is with reference to the position of the ultrasound probe. As the ultrasound probe is moved, the point of reference changes. Further, and even if the ultrasound probe is maintained in a relatively stable position, movements of deformable portions of the patient""s anatomy such as soft tissue can change the image data. In the case of such changed image data, it may be impossible or quite hard to tell whether the ultrasound probe has moved, the deformable anatomical portion has moved, or both. The ultrasound probe does not provide a fixed frame of reference for properly and readily positioning other medical devices. For example, if one wants to use a medical linear accelerator on the patient, a change in ultrasound image data may indicate that the anatomical portion being targeted has moved such that the patient and/or linear accelerator should be adjusted (usually the patient is moved) accordingly so that the moved target is hit. On the other hand, if the change in ultrasound data simply indicates a movement of the ultrasound probe, the linear accelerator should not be moved. Yet, the ultrasound probe cannot distinguish between those two situations.
Although many of the prior imaging techniques have been generally useful, they have often been subject to one or more of several disadvantages. They may require such bulky equipment that real time imaging is not possible during some medical procedures. Some techniques are unable to track anatomical changes sufficiently fast for certain situations. Some imaging techniques require movement of a device or patient to provide 3D data or they are limited to providing 2D data. Some prior imaging techniques do not provide imaging data relative to a fixed frame of reference such that use of the data in controlling or directing other medical techniques is difficult or impossible.
Accordingly, it is a primary object of the present invention to provide a new and improved imaging method and system.
A more specific object of the present invention is to provide imaging using a combination of imaging techniques.
A further object of the present invention is to provide real time imaging, while allowing ready access to the patient for performing other medical procedures.
Yet another object of the present invention is to provide real time imaging without requiring relative movement between a patient and an imaging device.
Yet another object of the present invention is to provide 3D imaging data.
Yet another object of the present invention is to provide imaging data relatively quickly.
Yet another object of the present invention is to provide imaging data relative to a fixed frame of reference or otherwise especially well-suited to be used in performing medical procedures.
The above and other features of the present invention which will be more readily understood when the following detailed description is considered in conjunction with the accompanying drawings are realized by a method including imaging at least a portion of a patient with a first imaging technique to provide a first set of imaging data, the first set of imaging data having a fixed frame of reference. Further, the method uses imaging at least a part of the patient with a second imaging technique, the part of the patient including at least some of the portion of the patient. The second imaging technique uses an ultrasound device to provide a second set of imaging data, the second set of imaging data being 3D data relative to the ultrasound device and not being fixed relative to the fixed frame of reference. The ultrasound device is operable to provide the 3D data without relative movement between the ultrasound device and the patient. Position data for the ultrasound device is determined. Using the determined position data and the second set of imaging data, a converted set of imaging data corresponding to the second set of imaging data being referenced to the fixed frame of reference is provided. The converted set of image data is combined with at least some of the first set of imaging data to provide a composite set of imaging data.
Preferably, the first imaging technique as used to provide the first set of imaging data is selected from the group consisting of: computerized tomography imaging, magnetic resonance imaging, and fluoroscopic imaging. In one method of the invention, the first imaging technique is performed and completed prior to the imaging with the ultrasound device.
The step of imaging with the ultrasound device uses an ultrasound probe that produces 3D imaging data without relative movement between the ultrasonic probe and the patient. The step of determining position data for the ultrasound probe includes determining the position of a plurality of probe position markers on the ultrasound probe, the position of the probe position markers being determined by a technique not including the first and second imaging techniques. The position of the ultrasound probe is determined using infrared (IR) imaging
A medical procedure is performed on the patient using both a medical device and the converted set of imaging data to determine positioning of the medical device relative to the patient. The medical device is a medical linear accelerator. Relative movement is caused between the patient and the medical device to bring the second set of imaging data into registry with the first set of imaging data. The method further includes the step of, at least before completion of the first imaging technique, securing a plurality of patient position markers fixed relative to the patient.
The method of the present invention may alternately be described as including the step of securing a plurality of patient position markers fixed relative to a patient, the patient position markers defining a fixed frame of reference. At least a part of the patient is imaged using an ultrasound device to provide an ultrasound set of imaging data, the ultrasound set of imaging data being 3D data relative to the ultrasound device and not being fixed relative to the fixed frame of reference. The ultrasound device is operable to provide the 3D data without relative movement between the ultrasound device and the patient. Position data for the ultrasound devices determined. The determined position data and the ultrasound set of imaging data are used to provide a converted set of imaging data corresponding to the ultrasound set of imaging data being referenced to the fixed frame of reference.
Preferably, the patient position markers are secured directly to the patient. The step of imaging with the ultrasound device uses an ultrasound probe that produces 3D imaging data without relative movement between the ultrasound probe and the patient. The step of determining position data for the ultrasound probe includes determining the position of a plurality of probe position markers on the ultrasound probe, the position of the probe position markers being determined by a technique not including ultrasound. The position of the ultrasound probe is determined using infrared (IR) imaging.
A medical procedure is performed on the patient using both a medical device and the composite set of imaging data to determine positioning of the medical device relative to the patient. The medical device is a medical linear accelerator.
The method of further includes the steps of: imaging at least a portion of a patient with a non-ultrasound imaging technique to provide a set of imaging data relative to the fixed frame of reference, and combining the converted set of image data with at least some of the set of imaging data from the non-ultrasound imaging technique to provide a composite set of imaging data. The non-ultrasound imaging technique is selected from the group consisting of: computerized tomography imaging, magnetic resonance imaging, and fluoroscopic imaging.
The system of the present invention is described as a system for carrying out medical procedures includes: a plurality of patient position markers operable for fixing relative to a patient to define a fixed frame of reference; an ultrasound device operable to provide an ultrasound set of imaging data, the ultrasound set of imaging data being 3D data relative to the ultrasound device and not being fixed relative to the fixed frame of reference, the ultrasound device being operable to produce 3D data without relative movement between the ultrasound device and the patient; a position determiner to determine position data for the ultrasound device relative to the fixed frame of reference; and a processor operable to use the determined position data and the ultrasound set of imaging data to provide a converted set of imaging data corresponding to the ultrasound set of imaging data being referenced to the fixed frame of reference.
The ultrasound device is an ultrasound probe that produces 3D imaging data without relative movement between the ultrasound probe and the patient. There are a plurality of probe position markers on the ultrasound probe. The position determiner includes a subsystem to determine the position of the probe position markers and the patient position markers. The subsystem includes an infrared (IR) camera.
The system further includes a medical device for performing a medical procedure on a patient using both the medical device and the ultrasound set of imaging data to determine positioning of the medical device relative to the patient.
A non-ultrasonic imaging subsystem is included and is operable to image at least a portion of a patient to provide a set of imaging data relative to the fixed frame of reference. The processor is operable to combine the imaging data from the non-ultrasonic subsystem with the composite data to provide a composite set of imaging data. The non-ultrasonic imaging subsystem is selected from the group consisting of: a computerized tomography system, a magnetic resonance system, and a fluoroscopy system. The medical device a medical linear accelerator.